Safety hook



March 25, 1958 v w. D. HiJMPHREY ET'AL 2,828,033

SAFETY HOOK 2 Sheets-Sheet 1 Filed Nov. 28, 1956 Mania Tirka wma llh rmf INVENTORS March 1958 w. D. HUMPHREY ETAL 2,8 ,0

v SAFETY HOOK Filed Nov. 28, 1956 FIG. 2

2 Sheets-Sheet 2 U d Saws tQ SAFETY HOOK William D. Humphrey, Fair Oaks, and Martin Teske, Vallejo, Calif.

Application November 28, 1956, Serial No. 624,953 3 Claims. c1. 214-317 (Granted under Title 35, U. S. Code (1952), sec. 266) *Theinvention described herein maybe manufactured and used by or for the Government of theUnited States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to hoists and more in' particular tosafety hooks for use in conjunction withsuch hoists as commonly are used on dump trucks of the type used to pick up filled containers and transport them to dumping locations. I

The particular type of dump truck for which the present invention is specially adapted is that known by the registered trademark Dempster-Dumpster, although as later will be appreciated, the principles of the invention also relate to other container hoists or dump trucks which utilize equival nt arrangements. Although a thorough understanding of such trucks is not presently necessary, referencecan be made to a number of U .S. patents such as Patent No. 2,369,722, issued February 20, 1945, to G. R. Dempster. Among the features to be specifically noted is first that they are provided at the rear of their frame with a tilted or inclined skid frame adapted to support a'container as it is being raised to or lowered from a transporting ordumping position. Further, although the containers for which the trucks are adapted may be rectilinear, cylindrical or shaped in other manners, each has a particular wall that engages the skid frame'and usually this wall is provided with a bail by which the container is grasped when a dumping operation is desired. The hoisting means usually are chains that engage lugs extending outwardly from either side of the container and the hoisting power customarily is hydraulic.

When a full container is to be picked up, the side lugs are engaged with the chainsand the hoist operated. in the initial part of the container-lifting operation, the container is slid upwardly along a vertical apron at the rear of the truck until it reaches a certain point. At this point,

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provide means for maintaining such a container in close adjacency with its skid frame. Afurther object is to provide such a means which is capable of operating in theaforesaid manner without otherwise interfering with the other operations such as the lifting, the dumping and'the lowering of the container.

Other objects will become apparent in the following description: 7

According to the present invention, hook means are slidably mounted on the central beam of the skid frame, these means being so disposed and dimensioned as to engageably receive some portion of the container, such as the bail, as the container is being lifted. Most preferably, the hook means have a stop member limiting their downward sliding movement so as to position the hooks forreceiving the bail immediately after the container has been brought to rest on the skid frame and raised a slight amount. I

. Another feature of importance is that the hooks being ;slidable retain their engagement during the lifting and the lowering of the container. Preferably, a pair of books are provided and the pair is spaced laterally a sufilcient distance for straddling the dump book which, as has been stated, is provided at the upperend of the central skid beam. Thus, the dump hook can act in its normal manner, even though the bail is engaged by the pair of safety hooks. Also, when the empty container is lowered,

the pair of books slide along until engaged by their stop i member at which point any subsequent lowering of the container frees the bail and permits the container to continue its downward descent along the vertical apron to the ground or base platform.

The preferred embodiment of the invention is illustrated in the accompanying drawing of which Fig. 1 is a somewhat diagrammatical view of part of the rear end the weight of the container, plus the pull of the hoist mechanism on it causes the container to tilt backwardly onto the inclined skid frame along which it is raised to dumping position. Normally, the skid frame has a central skid beam at the upper end of which is a dump hook and engages the bail when it reaches the upper level so that, if desired, the chains can be slackened to permit the bottom of the container to drop open or to permit such other dumping operation as may be peculiar to the particular container.

. One of the ditficulties experienced with dump trucks of this typehas been that thecontainers, instead of riding snugly against the backwardly tilted frame, tend to tilt or" a truck which carries the present hook; Fig. 2 is a side elevation of the truck center rail illustrating the manner in which the hook means of the invention engages a typical container; and Fig. 3 a side view of the hook meansl Referring to the drawings, the truck, which for pres-.

ent purposes can be considered substantially like the truck illustrated in the above-mentioned patent, includes such elements as a backwardly inclined skid frame 1 having a central skid beam 2, a rear vertical apron portion 3 which, as seen,is part of the truck frame, and hoist mechanism generally indicated by the numeral 4. The hoist mechanism usually is formed of a pair of rigid hoist arms 6 pivotally mounted on the frame and carrying hoist chains 7 provided with links 8 adapted to engage the containers.

As to the containers, it has been previously mentioned that these may be of. most any configuration. The particular container it) illustrated in Fig. 2 is rectilinear and is formed with sidewalls 9 each of which have outwardly extending lugs 12 for engagement with chain links 8. Further, this container has front and rear walls 14 and 16 and, as presently conceived, rear wall 16 is the Wall customarily slid along and supported by skid frame 1. Accordingly, wall 16 has mounted at its upper portion a bail 17 although, so far as the purposes of the present invention are concerned, any other like projection of this wall would suffice. As previously mentioned, bail 17 conventionally is provided to permit the dumping operation and this dumping is achieved by engaging the bail in a.

dump hook fixedlymounted at the upper end of central skid beam 2.

The important feature of the present inventionjis the" provision of a safety book 21 adapted to hold container 10 rather firmly against skid frame 1 so as to eliminate the possibility of spillage due to outward tilting of the container when unbalanced loads are encountered. As

Patented Mar. 25, 1958 bestmayhe 'seen in'Fig. 3, hook means 21 is formed of a sleevemember 22 provided with front, side and rear walls 23, 24 and 26, rear wall 26 being detachably secured to side walls 24 by means ofbolts 27. Such a detachable mounting is most-desirable to permit ready replacement or maintenance of -the-hooks as the need arises. Further, hook means 211 includes -a pair of latera'lly spaced-hook arms 28 which, preferably, are in require very little maintenance or present very few -fitlltl88z However, as previously claimed, the sleeve-of illustration these means are formed by a sleeve member 31 adjust-ably mounted on'central beam'Z, this sleeve being adjustable in any suitable manner to permit initial positioning of hook arms 28' at the most propitious location for engaging container" bail 17 as the container is being lifted. Obviously, in an arrangement such as is illustrated in the drawings, these stop members could be eliminated and the upper edge of apron 3 used as a stop for the downward sliding movement of the sleeve. However, in such an event either the sleeve or the extension of the hook arms would have to be especially dimensioned for the particular job to be performed.

Briefly summarizing the operation'of the apparatus, chains 7 first are engaged with lugs 12 of the container and the hoist mechanism actuated to initiate the container lifting. The container first rises vertically along apron 3- until the rearward pull of chains 7, as well as the anticipated top-heaviness of the container load itself, causes the container totilt backwardly into contact with skid frame 1. It is obvious that positioning of hook arms 28' must at this point be above bail l7 of'the container so that subsequent continued operation of the hoist means will pull the bail upwardly beneath the hook arms. Duringany subsequent lifting or lowering of the container,

the hook means is made in two parts so that it is an extremely simple operation to'replace a bent or worn hook with another. It also should be apparent that the hook means provided does not interfere in any way with the normal operations of the dump truck such as, for example, the hoist dumping or'lowering away of the containers.

Obviously nd-any modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is: n V I 1; Apparatus for engaging and hoisting a container, said apparatus comprising a skid-frame having a central skid beam coextensive with said skid frame for slidably engaging supporting and guiding a wall of a container during hoisting, in'eans for sliding a container up and down along saidirrame, safety hook means for engaging a portion'of a container as it is slid upwardly along the cen't'ral skid beam and having a downwardly-facing u shaped hook arm disposed for engaging such a porti'onpsa'i'd hook means comprising means for slidab ly mounting it on the said skid beam for movement throughout the length of said beam whereby said hook is capable ofsli'ding upwardly and downwardly along said central beam for maintaining its engagement during the lifting and. lowering of a container and for holding a container wall against said central beam, 7

2'. A safety hook for use with an apparatus for engaging and hoisting a container, the apparatus having a.

the hook arms being slidable along central beam 2,

" top of the skid frame, hook arms 23 straddle the dumping. hook and permit the bail to be engaged by' this hook, Preferably, such a dump hook is a spring-loaded type of book provided with suitable cams for permitting the engagement and also for permitting the release of the bail' by the dump hook after the dumping operation has been completed. One such hook is illustrated and described in the Dempster patent previously cited. As previously explained, the dumping operation is accomplished'by operating the hoist to produce a slack in the hoist chains and the container is so constructed that such a"slack perrnits its bottom to fall open.

The descent of the container after dumping is the same as the lifting operations to the extent that hook arms 28 retain engagement of bail 17. However, when sleeve 2'2' of hook means 21 strikes limit sleeve 31 which is mounted on the center rail, any further lowering of the container frees bail 17. Thus, continued lowering perrnits the container to slide downwardly along apron'3 to the ground.

As now should be apparent, the invention provides a quite simple but thoroughly effective means for absolutely preventing spillage of the containers due to outward tipping. The means provided obviously is an inexpen sive; easilyfabricated and durable element which should back'wardly-tilted skid frame provided with acentral skid bearncoextensive with said skid frame for slidably engaging Supporting and guiding a wall of a container during hoisting and also having a dumping hook mounted. on the upper portion of the beam for engaging bail means provided on the skid-engaging wall of a container, said safety hook comprising a sleeve body portion mounted in a freely-slidable manner on said central skid beam, hook means projecting from said sleeve for receiving said bail as the container is hoisted along said skid frame, and stop means for positioning said sleeve andhook for initial reception of the bail, said hook means functioning during said hoisting to maintain a container in close adjacency with the central skid beam. 7

3'. A safety hook for use with a container hoisting. mechanism having a backwardly-tilted skid frame provided with a central skid beam coextensive with the skidframe for 'slidably engaging supporting and guiding a wall of a container during hoisting and a dumping hook mount ed on the upper part of the beam-forengaging a bail means provided. on the skid-engaging wall of a container, said safetyhook comprising sleeve means mounted in a freely-slidable manner on the central skid beam, a pair of spaced-apart hookarms carried by and projecting outwardly and downwardly of said sleeve means for receiving a bail. as a container carrying a bail is hoisted on the skid frame, said hookarms being spaced one from the other sufliciently for straddling a said dumping hook,

References. Cited in the fle of this patent UNITED STATES PATENTS Eaton July 27, 19 43 Dempst'er Feb. 20, 1945 

